The proposed research is designed to contribute to the understanding of the prophylactic and therapeutic action of vitamin A and synthetic analogues on some neoplasms. Specific attention will be given to the cellular binding proteins for vitamin A, particularly from humans. The main objectives will be to develop antibodies against human binding proteins for radioimmunoassay and immunolocalization. These methods will be used to characterize human cancers and precancerous states. Techniques will be developed in model rat systems.